Biomedical subjects

T Nagata

Publications and source records attributed to T Nagata.

At least 307 records · Page 17Linked to original sources

PubMed1995

The pcsA gene is identical to dinD in Escherichia coli.

The pcsA68 mutant of Escherichia coli is a cold-sensitive mutant which forms long filaments with a large nucleoid in the central region at 20 degrees C. We here show that (i) the coding region for the pcsA gene is identical with orfY located upstream of pyrE and can be deleted without loss of viability; (ii) pcsA is also identical to dinD, a DNA damage-inducible gene, whose expression is regulated by the LexA-RecA system; (iii) the cold-sensitive phenotype of the pcsA68 mutation is suppressed by delta recA or lexA1 (Ind-) mutation, but not by sulA inactivation; (iv) overproduction of PcsA68 leads to inhibition of cell growth in recA+ and delta recA strains at 20 and 37 degrees C, but PcsA+ does not show such an effect at any temperature; (v) SOS response is induced in the pcsA68 mutant cells at 20 degrees C. We discuss the possible function of the pcsA gene, comparing it with the sulA or the dif-xerCD function. We also describe a new method for gene disruption with positive and negative selection.

Bacterial Proteins↗

PubMed1995

Light microscopic autoradiographic study of DNA synthesis in cecal epithelial cells of aging mice.

The localization and activity of DNA synthesis of mouse cecal epithelia from prenatal Day 19 embryos to 12-month adults were investigated by light microscopic autoradiography after [3H]-thymidine injection in vivo. The cecal epithelial labeled cells with [3H]-thymidine were located at the lower half of the crypts, and the labeling index (LI) changed with the development of the cecum due to aging. A peak in the LI of absorptive cells was found at embryonic Day 19, but it decreased strikingly at the first postnatal day and then kept an almost constant value until 12 months. The LI of the goblet cells showed the highest value at fetal Day 19, decreased gradually with aging from the first postnatal day, and completely disappeared from 1 month onwards. The basal granulated cells were located only in the base of crypts, and the significant difference of LI was not found from embryonic Day 19 through 12-month adult. The results obtained in this study suggest that there are some differences of DNA synthesis among different kinds of cecal epithelial cells from embryonic stages to postnatal stages as a result of aging.

Aging↗

PubMed1995

Cloning and nucleotide sequence of the inulin fructotransferase (DFA I-producing) gene of Arthrobacter globiformis S14-3.

A gene encoding an inulin fructotransferase (DFA I-producing) [EC 2.4.1.200] from Arthrobacter globiformis S14-3 was cloned and the nucleotides sequenced, for the first time. The sequence indicated that the native enzyme protein is composed of 392 amino acid residues. The native enzyme is an extracellar enzyme produced in the culture supernatant of A. globiformis S14-3, but the nucleotide sequence of the gene lacks a sequence for signal peptide for secretion. The 1.5-kb DNA fragment encoding the gene was found to produce the active enzyme in the culture supernatant of an E. coli clone, under the control of the lac promoter of pUC119.

Amino Acid Sequence↗

PubMed1995

Studies on the factors affecting the recording of somatosensory evoked potentials induced by tibial nerve stimulation in dogs.

Since spinal cord abnormalities are often associated with lesion in the thoracic or lumber vertebrae, examination of Somatosensory evoked potential (SEP) induced by hind limb nerve stimulation will be useful. In the experiment, scalp recorded SEP in dogs by tibial nerve stimulation was studied on the distribution, the change of latency by body size and the influence of experimental compression to the spinal cord. Greatest response was got at Fz, and shorter latencies for SEP recorded on the ipsilateral stimulation side than from the contralateral side. The equation describing the regression line of the latency with the distance to the recording site from stimulating site was Y = 0.072X+13.23 and the regression was statistically significant. In the experimental study of compression to spinal cord, dorsal compression tended to be sensitive compared to the ventral compression. This study suggested that not only increase of latency but also reduction of amplitude could occur as a result of spinal cord disorders.

Animals↗

PubMed1995

Physiological concentrations of retinoic acid suppress the osteoblastic differentiation of fetal rat calvaria cells in vitro.

The effects of retinoic acid (RA) on osteoblastic differentiation and activity were studied in fetal rat calvaria cells cultured for up to 24 days. Fetal bovine serum used for the experiments was treated with an anion-exchange resin to remove endogenous RA. The depletion of RA in the treated serum was confirmed by high-performance liquid chromatography and tritiated RA tracing. Under the culture conditions employed, the continuous presence of RA for 14 days at 10(-9) mol/l or higher decreased both alkaline phosphatase (ALP) activity on day 12 and the number of bone nodules on day 14 in a dose-dependent manner. Short-term (24 h) exposure to RA at 10(-8) mol/l, which is a physiological concentration, decreased and increased the levels of ALP and osteopontin mRNA on day 6, respectively. Retinoic acid at 10(-8) mol/l also increased the level of osteocalcin mRNA on day 12. However, these effects were not obvious at later stages (days 18 and 24). At a high concentration (10(-6) mol/l), RA increased the level of osteopontin mRNA on day 6 and decreased the levels of ALP and osteocalcin mRNA irrespective of culture period. These results suggest that, at physiological concentrations, RA suppresses the differentiation of osteoprogenitor cells and regulates osteoblastic functions.

Alkaline Phosphatase↗

PubMed1995

Factors influencing nifedipine-induced gingival overgrowth in rats.

Factors such as age, the dose of nifedipine administered in the diet, serum drug level, duration of drug administration, and sex which may influence nifedipine-induced gingival overgrowth were examined in a rat model using 20-, 50-, and 90-days-old male and female rats. Oral administration of nifedipine (50 to 250 mg/kg diet) increased the serum level of the drug in a dose-dependent manner in both males and females. However, a higher serum level was required in females than males to attain the same degree of gingival overgrowth. The minimum dietary concentrations of the drug required to elicit gingival overgrowth in males and females were 150 and 100 mg/kg, respectively, which gave respective minimum serum levels of 800 and 1100 ng/ml. The degree of overgrowth depended on the serum concentration of the drug after it had reached the required minimum in male and female animals. Administration of nifedipine (250 mg/kg diet) for 20 days was enough to induce maximal overgrowth, but this induction occurred only in rats that started to receive the drug when they were 20 days old, not in those that started at 50 and 90 days of age for the same administration period of 55 days, and the overgrowth regressed and the gingiva were normal 40 days after ceasing drug administration. These results suggest that gingival overgrowth occurred in accordance with the drug concentration in the diet, as well as that in the serum, and was more likely to occur in males and younger individuals.

Age Factors↗

PubMed1995

Morphometry in anatomy: image analysis on fine structure and histochemical reactions with special reference to radioautography.

Anatomy now has a step to transfer from qualitative science to quantitative science. The methods of anatomical investigation employ optical instruments. Anatomy initially described qualitative features of the structure of the body, but now it turns to transfer to new fields measuring the number, size, length, area and volume of not only, structure but also the histochemical components of the structure with quantitative analysis. In order to quantify histochemical reactions in various organs, light and electron microscopic radioautograms were prepared from the liver, pancreas, intestines and kidney which were labeled with 3H-thymidine, 3H-uridine, 3H-leucine, 3H-glucosamine and 3H-glycerol, fixed in glutaraldehyde and osmium tetroxide, embedded in Epoxy resin, sectioned either thick or thin, coated with either Konica NR-M2 or -H2 radioautographic emulsions, exposed, developed, stained for either light or electron microscopic radioautographs. The radioautographs were observed with Olympus Vanox AHB-LB or Nikon Optiphot-2 light microscopes or Hitachi H-700, JEOL JEM-4000EX electron microscopes at 200 and 400 kV. The radioautograms were analysed with various image and analysed such as PPA-250, MOP, Digigramer-G, IBAS-II, Quadra 900, Luzex 300 to count the number of silver grains and to measure the size and number of structures. Some electron microscopic radioautographs were analysed in analytical electron microscopes, combined with Hitachi H-700 Horiba EMAX-1800E, JEOL JEM-200CX Kevex 7000-77, and JEOL JEM-4000EX Tracor-Northern TN-5400 to quantify silver grain contents. The results demonstrated that correct data can be obtained by controlling both full-automatic and semi-automatic image analysers by operating them manually.

Anatomy↗

PubMed1995

Radioautographic study of the macromolecular synthesis of Leydig cells in aging mice testis.

The studies on DNA, RNA and protein synthesis of Leydig cells in aging mice testis of several groups were carried out by light microscopic radioautography. The cells labelled with 3H-thymidine, 3H-uridine and 3H-leucine were observed in various aging groups. The labeling index with 3H-thymidine was low at embryonic and early postnatal stages. It increased slightly at 6 months, reached its peak at 9 months and maintained a relatively high level at a later period. The number of the silver grains labelled with 3H-uridine over the nuclei and cytoplasm were observed from embryonic day 19 and increased from 3 months onwards. From adult to old ages, the activity of 3H-uridine incorporation was maintained at a high level in the nuclei and a relatively low level in the cytoplasm. The aging change of 3H-leucine incorporation was found from this experiment. The labeling indices between embryonic and early postnatal stages showed no obvious differences while the number of the silver grains over both cytoplasm and nucleus increased from 6 months onwards and was maintained a high level until old age.

Aging↗

PubMed1995

Nucleic acid synthesis in the developing mouse ovary, uterus and oviduct studied by light and electron microscopic radioautography.

The DNA and RNA synthesis in the developing mouse ovary and oviduct were studied by 3H-thymidine and 3H-uridine radioautography. The results showed that both DNA and RNA syntheses were active in all surface epithelial cells, in stromal and follicular cells of the ovaries between postnatal days 1 to 7; then they decreased significantly from day 14 on. However, the DNA synthesis in the epithelial and in the stromal cells of the uteri and oviducts was active at days 1 and 3 and decreased from day 7. The RNA synthesis in the uteri and oviducts was active at postnatal day 1, increased from postnatal day 1 to day 14, decreasing between days 30 to 60. An unparalleled alternation of the DNA and RNA synthesis was shown between the ovary and uterus or oviduct. After postnatal day 3, the RNA synthesis was more important in the uterus and oviduct than in the ovary.

Animals↗

PubMed1995

Death due to asphyxia linked to antipsychotic drugs.

A 46-year-old man with schizophrenia, died in hospital. Autopsy revealed numerous facial injuries and the direct cause of death was apparently asphyxia as a large amount of coagulated blood was present in the lower part of the trachea and bronchi. The blood derived from a lacerated wound of the mouth. The question was raised as to why expectoration was impossible and a toxicological analysis was directed to the antipsychotic drugs allegedly prescribed by doctors at the hospital. Using gas chromatography and gas chromatography/mass spectrometry, four different antipsychotic drugs including chlorpromazine, levomepromazine, zotepine and haloperidol were identified in the whole blood and tissues with concentrations being 1.91, 0.75, 0.61 and 0.48 micrograms/g in the blood, respectively. These levels were toxic to the extent that he could not expectorate and blood accumulating in the airway led to asphyxia and death.

Antipsychotic Agents↗

PubMed1995

[Uptake of Tc-99m hexakis 2-methoxy isobutyl isonitrile in lung or mediastinal lesions by SPECT].

The uptake of Tc-99m hexakis 2-methoxy isobutyl isonitrile (99mTc-MIBI) was evaluated in 18 patients with various lung or mediastinal lesions by SPECT. The patients consisted of seven with lung cancers, three with lung cancers who were treated with chemotherapy and were disease free, and one each with malignant lymphoma, esophageal cancer, thyroid cancer involving the mediastinum, malignant thymoma, pneumonia, granuloma, sarcoidosis and neurinoma. SPECT imaging (30 min, 600 MBq) was performed after intravenous injection. Strong uptake of 99mTc-MIBI was noted in all malignant tumors except malignant lymphoma. The mean tumor to normal lung tissue uptake ratio (T/N ratio) was 2.26. The mean in lung cancer was 2.31. Slight accumulation was present in pneumonia and granuloma (mean T/N = 1.24). No accumulation was present in a case of non-Hodgkin's lymphoma and neurinoma. Moderate uptake was noted in one case of sarcoidosis (T/N = 1.46). No abnormal accumulation of 99mTc-MIBI was seen in post-therapeutic lung cancer. These results suggested that 99mTc-MIBI SPECT could be useful in differentiating between malignant and benign lesions.

Adult↗

PubMed1995

Brain death diagnosed by forensic analysis of drug distribution in human tissues.

Brain death was diagnosed by analyzing drug distribution in human tissues. Concentrations of diazepam and phenobarbital in human tissues, administered therapeutically to 3 patients in a critical condition, were determined by gas chromatography with a nitrogen phosphorus detector and gas chromatography-mass spectrometry. In 2 patients administered drugs while the brain was functioning, drug concentrations in the brain were high compared with those in the other tissues. In the other patient given the drugs after vital signs of the brain ceased, the level of drugs in the brain was much lower than seen in other tissues. We propose that a forensic diagnosis of patients who are brain dead can be made by comparing the concentrations of drugs in the brain given at the time of critical condition with concentration of these agents in other tissues. When cerebral function ceased can be roughly estimated by the variable distribution patterns of drugs and time of administration of these drugs.

Adult↗

PubMed1995

Incorporation of 3H-amino acids by endometrial stromal cells during decidualization in the mouse. A radioautographical study.

The incorporation of 3H-amino acids by endometrial stromal cells was analyzed by radioautography during decidualization in the mouse. 3H-proline was administered to 5- and 6-day pregnant mice and to virgin mice in estrus used as controls. 3H-tryptophan was administered to 6-day pregnant mice. The animals were killed 30 min. after the injection of the radioactive label. The quantitative analysis of the radioautograms showed that the concentration of silver grains per unit area due to 3H-proline incorporation was higher in decidual and predecidual cells on the fifth and sixth day of pregnancy than in fibroblasts of virgin mice. Considering the pregnant endometrium by itself, the incorporation of both 3H-proline and 3H-tryptophan was higher in fully differentiated decidual cells and predecidual cells than in fibroblasts of the periphery of the endometrium and involuting decidual cells. These results show a clear correlation between different endometrial regions recognized by morphological criteria and their metabolic activity. The data also show that different cells of the pregnant endometrium have different metabolic activities, independently of the precursor that was used.

Animals↗

PubMed1995

Age-related changes of male mouse submandibular gland: a morphometric and radioautographic study.

The DNA synthesis and the changes of cell population kinetic of aging male mouse submandibular glands were studied by light and electron microscopic radioautography from embryonic day 19 to 21 months postnatal. At the embryonic day 19, the gland consisted of developing acinar cells (49%), intercalated duct (ICD) (37%), juxta-acinar (JA) (3%) and striated duct (SD) cells (11%). At birth, JA cells increased rapidly to 32%, thereafter decreased gradually. At 1 month of age, granular convoluted tubule cells appeared and increased rapidly in number with age. They reached a maximum at 6 month after birth. Then they appeared to decrease gradually from 6 to 21 months. The most conspicuous feature of the aged submandibular glands was the regressive changes of the granular ducts. The extent and height of the granular ducts as well as the content of mature secretory granules decreased. These changes may play an important role during the development of mice, because the granular duct synthesizes many biological factors. The 3H-thymidine labeling index of each cell type of male mouse submandibular glands reached a peak 1 day after birth and decreased with aging. The labeling index of intercalated duct cells was higher than the others and persisted for a long time. On the other hand, the labeling indices of the other cells were significantly depressed at one week after birth. From these observations on morphology, it was also shown that ICD cells were concerned with the generation of the other cell types.

Aging↗

PubMed1995

Ultrastructural and radioautographic studies on DNA synthesis in Leydig cells on aging mouse testis.

A morphological observation and a radioautographic study were carried out to detect the ultrastructure and aging changes of DNA synthesis of the Leydig cells, whose structure has been observed and the area of the lipid droplets in the cytoplasm calculated. The observation by electron microscopy showed that Leydig cells contained abundant mitochondria and endoplasmic reticulum and that the area of the lipids in the cytoplasm changed with aging. Only little lipid droplets were found in embryonic and early postnatal stages, but they increased from postnatal two weeks onwards and no significant differences were found from 9 months to 21 months. The DNA synthesis in these cells was not vigorous at embryonic day 19, explored by light microscopic radioautography 1 hr. following a single injection of 3H-thymidine. The labeling index increased slightly before six months of age and reached its peak at 9 months. There was no significant difference found in the number of labelled cells from that time on. A relatively high level was maintained at adult and senescent periods. Our results demonstrate that the generation of the Leydig cells contained plentiful lipid droplets was vigorous at adult and senescence.

Aging↗

PubMed1995

Study on nucleic acid synthesis in mouse retina and retinal pigment epithelium by radioautography.

The ocular tissues of ddY mice from embryonic 9 to postnatal day 14 were labelled in vitro with 3H-thymidine or 3H-uridine. After radioautography, the radioautographs were observed by light and electron microscopes. The labeling indices (L.I.) with 3H-thymidine or grain numbers with 3H-uridine were calculated and the area (microns 2) of cell organelles in both labelled and unlabelled retinal cell with 3H-thymidine were measured by image analysis. The L.I. of retinal cells were low in the beginning then increased and reached a peak at P3, while the L.I. of retinal pigment epithelium (RPE) increased and reached a peak at P7. The L.I. of both retinal and PE cells disappeared at P14. However, the L.I. of anterior region were more than those of equaterial and posterior regions in both retinal and PE cells. The results of the image analysis showed that the average area of cell organelles, both labelled and unlabelled retinal cells decreased from E9 to P14. The grain numbers of retina labelled with 3H-uridine increased until P1 then decreased, while the numbers of RPE increased and reached a peak at P3 whereafter they declined. No significant differences were detected among the three regions.

Animals↗

PubMed1995

Light and electron microscopic radioautographic studies on macromolecular synthesis in digestive organs of aging mice.

For the purpose of analyzing the changes of macromolecular synthesis in aging animals, we have developed methodologies for quantitative light and electron microscopic radioautography. The methodologies were applied to DNA, RNA, protein, glucides and lipids syntheses of digestive organs, especially of the liver and the pancreas of aging strain ddY mice, demonstrating the incorporations of respective precursors, 3H-thymidine, 3H-uridine, 3H-leucine, 3H-glucosamine, 35S-sulfuric acid and 3H-glycerol. Characteristic differences have been observed between the respective macromolecular syntheses in respective aging groups, from prenatal (embryonic day 19) to postnatal newborn period (postnatal day 1), from suckling (postnatal day 3) to weaning (postnatal day 14), juvenile (postnatal 1 month), young adult (postnatal 2 month) and senescent periods (6 and 12 months up to 2 years). These results are extensively analyzed and reviewed.

Aging↗

PubMed1995

Three dimensional observation of whole mount cultured cells stained with histochemical reactions by ultrahigh voltage electron microscopy.

Thick biological specimens prepared as whole mount cultured cells stained with histochemical reactions, such as thiamine pyrophosphatase, glucose-6-phosphatase, cytochrome oxidase, acid phosphatase, DAB reactions demonstrating specific cell organelles such as Golgi apparatus, endoplasmic reticulum, mitochondria, lysosomes, peroxisomes and pinocytotic vesicles, were observed by ultrahigh voltage electron microscopy at accelerating voltages of 400-1000 kV producing stereo-pairs. As a result, those cell organelles were observed 3-dimensionally and the relative relationships between these organelles demonstrated.

Acid Phosphatase↗